In 1942, Nazi engineers devised a plan to build a 1,500-ton supertank. The P1000 Rat, or "Land Cruiser," was to be the largest and fiercest industrial-age ground weapon the world had ever seen. In 1943, the project was cancelled. So how did its massive gun turret wind up on a coastal hilltop in Norway?

The Rat had been among the projects — almost supernatural in scope — with which Hitler would demonstrate Germany's industrial and military might. The shock-and-awe weapon would have served the dual roles of energizing the German populace and cowering state enemies with the sheer audacity of metal. Hitler called this "gigantism."

In early 1943, Hitler's Chief Armaments minister, Albert Speer, decided a monster-sized tank would be far too costly in resources, and provided too big a target for Allied forces — which by then had demonstrated bombs capable of destroying the P1000's thick armor — and cancelled the project.

But a turret for the P1000 had already been built. It was a variant on a naval heavy cruiser turret as used in Gneisenau-class battleships, fitted with a 280 mm SK C/34 naval gun. What would they do with gear (and firepower) of that size?

This is what they did. Years before, during WWI, a massive naval battle — the Battle of Jutland — raged in Northern Europe as the Germans' attempted to break a British naval blockade. The Brits controlled the Skagerrak, a strait running between Norway and the southwest coast of Sweden, which was then the strategic gateway to the Baltic and North Atlantic.

At the Western head of the Skagerrak, where the strait merged with the North Sea, sat Kristiansand, Norway. With WWII reviving the same old concerns about who would dominate the shipping lanes, the Germans invaded Denmark and Norway and mined the Skagerrak heavily.

And so, when deciding where to place their erstwhile super-tank's gun turret, they chose occupied Norway - in a location near Kristiansand overlooking the Skagerak. The massive weapon would provide additional protection against the Allies' battleships in that strategically significant area.

The cannon battery eventually became part of Hitler's "Atlantic Wall" of fortifications running along Europe's western coast, put in place to safeguard against an Allied invasion of the occupied mainland.

And there it still sits. It's a gun so huge it fairly dominates the Norwegian coastal countryside — and is clearly the most visible man-made object found on a sweep of Norway on Google Earth.

It's not the only one. Many other armaments along the Atlantic Wall were turrets taken from decommissioned ships.

But none of the others came from a never-built tank.

(The 3D rendering of the cannon in Google Earth was done by Dutch graphic artist Fingerz)